The present invention relates to rectangular balers of the type disclosed in U.S. Pat. No. 4,624,180, and more particularly to a method and means for indirectly monitoring the moisture content of the crop material being baled.
With the baler disclosed in the aforementioned patent it is possible for an operator to continue a baling operation even though the moisture content of the crop material is too high or too low. The operator first learns that the crop material is too dry when he looks behind the baler and sees a cloud of dust. A "too wet" condition becomes evident to the operator when the wet crop material begins to clog the baler. In either case, several bales containing poor quality hay are formed before the operator recognizes that the moisture content is outside acceptable limits.
In the Strosser patent a microprocessor-based control system monitors and controls a rectangular baler. One of the conditions controlled is the tension rail pressure, i.e. the pressure applied to side rails of the bale casing. The microprocessor monitors the force exerted on the connecting rods of a plunger which forces the crop material through the bale casing, and in response to the connecting rod force, adjusts the pressure on the tension rails so that a uniform crop density, selected by an operator, is maintained. It has been found that if the crop material is too dry, the coefficient of friction between the tension rails and the crop material being forced between the rails drops. This causes a drop in the connecting rod force. The microprocessor attempts to correct the condition by applying a higher pressure to the tension rails but there is a limit beyond which the hydraulic system may fail.
If the crop material is too wet, the coefficient of friction between the tension rails and the crop material increases thus causing an increase in the connecting rod pressure. To correct for this the microprocessor causes the tension rail pressure to be reduced but it cannot be reduced below zero. Thus, if the moisture content of the crop material is either too high or too low, the microprocessor is unable to adjust the tension rail pressure to obtain uniform bale density and in this event it is desirable that the operator be informed.